This invention relates to cosmetic compositions having characteristics consistent with those of the sebaceous skin or hair film.
It is known that sebum secretion is related to the protective functions of the skin since, by impregnating the horny layer of the skin, it normalizes heat conductivity and interferes with the drying effect of the atmosphere on the skin.
Therefore, in the cosmetic art, attempts have always been directed both to complying with integrity of epicutaneous sebaceous film, and to restoring said film with units having the same characteristics as sebum. However, these purposes have never been effectively attained because, on formulating such units, only the chemical features of normal sebaceous secretion have been taken into account.
Cosmetic compositions of the kind set forth above fall within two classes:
(a) Sebum-like units having the same characteristics as sebaceous film and exhibiting compensating and complementary effects of said film; and PA1 (b) Sebotropic units, suitable to cleanse skin and hair, while restoring the sebaceous film required and sufficient for cutaneous physiological defense. PA1 (1) Face sebum, HLB.sub.r =10.4-10.7 PA1 (2) Hair sebum, HLB.sub.r =12.4-12.8 PA1 (1) Formulation of sebotropical cosmetics, that is, emulsifying units having an emulsification value (HLB) equal to the required value of emulsification (HLB.sub.r) of sebum. PA1 (2) Formulation of sebum-like cosmetics, that is units having the same required value of emulsification (HLB.sub.r) as sebum. Both natural sebaceous film and artificial sebum-like units are included as distinguishing ingredients in these cosmetics. In any case, the normal sebaceous film is of essential importance, both as to cosmetic structure and fulfilment of cosmetological goals thereof.
Sebum-like cosmetics hitherto commercially available were always formulated to imitate the chemical characteristics of sebaceous secretion, without taking into account the well defined physical characteristics of sebum. When applying said products, to which it was intended to assign compensating and complementary effects of sebaceous film, the presence of said film on the skin and its incidence on topical forms was not kept in mind. As a matter of fact, said sebum-like cosmetics so far commercially available act upon the skin and its horny-like glandular formations by apposition, that is to say by being superimposed on the treatment zone where, to achieve the relevant cosmetological activity thereof, they break up the epicutaneous sebaceous film.
In hitherto commercially available sebotropic units, or units having a washing action for cleansing the skin and its productions, particularly hair i.e., soaps and shampoos, the cleansing phenomenon could never be controlled to remove excess sebum associated with dirt, complying with the sebaceous film required and sufficient for cutaneous physiological defense.
At present, physiology and biochemistry recognize that epicutaneous sebaceous film, in its natural function between the human body and surrounding environment, is the most efficient and immediate cutaneous protective system. Furthermore, pathology grants that the destruction and disorderly overthrow of its structure is equivalent to exposing the individual to unfailing disfunctional upsettings such as, for example, scurf resulting from capillary cleansing agents, skin reddening and allergic events due to awkward transcutaneous penetration of chemical agents.